1. Field of the Invention
The present invention relates to a system for decapsulating an integrated circuit package that is mounted to a printed circuit board.
2. Description of Related Art
Integrated circuits (ICs) typically contain a plurality of surface pads that are connected to the circuit of the IC. After fabrication the IC can be tested by placing probe pins of a device tester onto the surface pads. Integrated circuits are typically assembled into a package that is soldered to a printed circuit board. Some packages are constructed from a molded plastic material that encapsulates the integrated circuit. The integrated circuit becomes inaccessible to external test equipment after the plastic material is molded onto the IC. It is sometimes desirable to test the integrated circuit after the plastic is molded around the IC.
The integrated circuit can be exposed by decapsulating the plastic package within a device level decapsulation system (DLDS). The decapsulation system exposes a portion of the package to an etchant that removes the plastic material without attacking the underlying integrated circuit. The etchant is applied to the package until the surface pads of the IC are exposed to the ambient. Probe pins can then be placed onto the surface pads to test the integrated circuit.
It is sometimes desirable to test an integrated circuit after the IC is mounted to a printed circuit board. Debugging an individual integrated circuit after assembly to a printed circuit board presently requires the removal of the package from the board. The package is typically removed by applying heat to the assembly to reflow the solder joints. Reflowing and removing the package may damage the package leads, particularly packages which have fine high pitch lead counts. The reflow process also reduces the integrity of the board.
It is also desirable to test integrated circuits while the IC packages are still mounted to the printed circuit board. Final assembly tests are particularly desirable for high speed devices that are sensitive to the impedance of the circuit board. The device level decapsulation systems of the prior cannot expose the IC while the package is mounted to the printed circuit board. It is therefore desirable to provide a system that can decapsulate an integrated circuit package while the package is mounted to a printed circuit board.